For oil and gas exploration, information about subsurface formations that are penetrated by a wellbore is necessary. Measurements are essential to predicting production capacity and production lifetime of a subsurface formation. Collection and sampling of underground fluids contained in subterranean formations are well known. Moreover, testing of a formation may provide valuable information regarding the properties of the formation and/or the hydrocarbons associated therewith. In the petroleum exploration and recovery industries, for example, samples of formation fluids are collected and analyzed for various purposes, such as to determine the existence, composition and producibility of subterranean hydrocarbon fluid reservoirs. This aspect of the exploration and recovery process is crucial to develop exploitation strategies and impacts significant financial expenditures and savings.
A variety of packers are used in wellbores to isolate specific wellbore regions. A packer is delivered downhole on a tubing string or wireline, and a packer sealing element is expanded against the surrounding wellbore wall to isolate a region of the wellbore. The outer flexible skin or sealing layer of the sealing element is typically a uniformly-surface, cylindrical layer of rubber/elastomer.
Typically, a packer is restricted to drawing sample fluid from the formation for testing. However, the drawing of fluid, in and of itself, may not be sufficient for determining mechanical properties of the formation. Typical packer operation does not involve setting, at the essentially the same time and location, stresses in the formation near the wellbore and fluid flow rate through the formation wall. Moreover, it is not possible to measure the formation wall displacement at a location where stress is applied on the formation wall, while still permitting simultaneous flow into or from the formation at essentially the same location. Therefore, a method and/or system is desired for using a packer to determine mechanical properties of a formation, and to measure mechanical properties as a function of fluid flow and/or pressure.